1. Field of the Invention.
This invention relates to the testing of driveline components, in particular components having a large, variable inertia applied during normal operating conditions or during test conditions. More particularly still, this invention relates to a control system that accurately simulates the application of a large inertia to such a component during test conditions.
2. Description of the Prior Art.
The results produced by quality control testing of a torque transmitting, rotating component tested before its assembly in a motor vehicle will be more indicative of its performance under normal conditions if the dynamic conditions under which the test is conducted represent closely the actual operating conditions. One dynamic condition in which current test practice deviates substantially from vehicle conditions involves the inertia applied to the tested component. Ordinarily, a flywheel is provided which represents only a fraction of the large inertia of the vehicle, perhaps only 20-50% of the actual inertia. The size of the flywheel that would represent the entire vehicle inertia is unmanageably large. The time required to accelerate such an enormous mass to the desired velocity is prohibitively excessive, particularly so when tests are conducted in a high volume production environment such as a modern factory. Therefore, large inertia flywheel,s, even if they could be implemented successfully, are not used. To shorten the test cycle, smaller inertia masses have been used, but these do not represent sufficiently well the actual operating conditions.
A transmission responds to torque and velocity and to the time rate of change of these variables applied to both the input and output shafts of the transmission. Physical inertia imposes a proportional relationship between torque and acceleration, but the same relationship can be achieved by other means.
If a motor is fully controllable, any torque within its rating can be achieved independently of velocity or acceleration Proper control strategy can achieve any desired relationship between torque and acceleration including one which simulates inertia of arbitrary magnitude subject to the rated torque limits of the motor.